Cohort Profile: The National Longitudinal Study of Adolescent to Adult Health (Add Health)

Chlamydial and gonococcal infections are important causes of pelvic inflammatory disease, ectopic pregnancy, and infertility. Although screening for Chlamydia trachomatis is widely recommended among young adult women, little information is available regarding the prevalence of chlamydial and gonococcal infections in the general young adult population. To determine the prevalence of chlamydial and gonococcal infections in a nationally representative sample of young adults living in the United States. Cross-sectional analyses of a prospective cohort study of a nationally representative sample of 14,322 young adults aged 18 to 26 years. In-home interviews were conducted across the United States for Wave III of The National Longitudinal Study of Adolescent Health (Add Health) from April 2, 2001, to May 9, 2002. This study sample represented 66.3% of the original 18,924 participants in Wave I of Add Health. First-void urine specimens using ligase chain reaction assay were available for 12,548 (87.6%) of the Wave III participants. Prevalences of chlamydial and gonococcal infections in the general young adult population, and by age, self-reported race/ethnicity, and geographic region of current residence. Overall prevalence of chlamydial infection was 4.19% (95% confidence interval [CI], 3.48%-4.90%). Women (4.74%; 95% CI, 3.93%-5.71%) were more likely to be infected than men (3.67%; 95% CI, 2.93%-4.58%; prevalence ratio, 1.29; 95% CI, 1.03-1.63). The prevalence of chlamydial infection was highest among black women (13.95%; 95% CI, 11.25%-17.18%) and black men (11.12%; 95% CI, 8.51%-14.42%); lowest prevalences were among Asian men (1.14%; 95% CI, 0.40%-3.21%), white men (1.38%; 95% CI, 0.93%-2.03%), and white women (2.52%; 95% CI, 1.90%-3.34%). Prevalence of chlamydial infection was highest in the south (5.39%; 95% CI, 4.24%-6.83%) and lowest in the northeast (2.39%; 95% CI, 1.56%-3.65%). Overall prevalence of gonorrhea was 0.43% (95% CI, 0.29%-0.63%). Among black men and women, the prevalence was 2.13% (95% CI, 1.46%-3.10%) and among white young adults, 0.10% (95% CI, 0.03%-0.27%). Prevalence of coinfection with both chlamydial and gonococcal infections was 0.030% (95% CI, 0.18%-0.49%). The prevalence of chlamydial infection is high among young adults in the United States. Substantial racial/ethnic disparities are present in the prevalence of both chlamydial and gonococcal infections.